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CBSE Class 12 · 2006 · All India Compartment · BiomoleculesShort Answer

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a) What are denaturation and renaturation of proteins?
b) Give a reason: amylase present in the saliva becomes inactive in the stomach.

Solution

(a) \textbf{Denaturation} — the unfolding of a protein (2°/3° structure destroyed, activity lost) under heat or altered pH. \textbf{Renaturation} — if the native conditions return, some proteins refold into the original structure and regain activity.
(b) Salivary amylase works near pH 6.8; the stomach's HCl (pH ≈ 2) denatures it — hence it stops digesting starch there.

CBSE Class 12 Board · 2006 · All India Compartment · Subjective

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